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//                                                                       //
//               The Next Generation Logic Library                       //
//                                                                       //
///////////////////////////////////////////////////////////////////////////
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//  Copyright 2015-20xx Christoph Zengler                                //
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/******************************************************************************************
 * MiniSat -- Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
 * associated documentation files (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * The above copyright notice and this permission notice shall be included in all copies or
 * substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
 * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
 * OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 ******************************************************************************************/

package org.logicng.solvers.datastructures;

import org.logicng.collections.LNGIntVector;

import java.util.Comparator;

/**
 * A clause of the SAT solver for MiniSAT-style solvers.
 * @version 1.0.1
 * @since 1.0
 */
public class MSClause {

  /**
   * A comparator for clauses based on LBD and activity (used for the Glucose solver).
   */
  public static final Comparator<MSClause> glucoseComparator = new Comparator<MSClause>() {
    @Override
    public int compare(final MSClause x, final MSClause y) {
      if (x.size() > 2 && y.size() == 2)
        return -1;
      if (y.size() > 2 && x.size() == 2)
        return 1;
      if (x.size() == 2 && y.size() == 2)
        return 1;
      if (x.lbd() > y.lbd())
        return -1;
      if (x.lbd() < y.lbd())
        return 1;
      return x.activity() < y.activity() ? -1 : 1;
    }
  };

  /**
   * A comparator for clauses based on activity (used for the MiniSAT solver).
   */
  public static final Comparator<MSClause> minisatComparator = new Comparator<MSClause>() {
    @Override
    public int compare(final MSClause x, final MSClause y) {
      return x.size() > 2 && (y.size() == 2 || x.activity() < y.activity()) ? -1 : 1;
    }
  };

  private final LNGIntVector data;
  private final boolean learnt;
  private final boolean isAtMost;
  private double activity;
  private int szWithoutSelectors;
  private boolean seen;
  private long lbd;
  private boolean canBeDel;
  private boolean oneWatched;
  private int atMostWatchers;

  /**
   * Constructs a new clause
   * @param ps     the vector of literals
   * @param learnt {@code true} if it is a learnt clause, {@code false} otherwise
   */
  public MSClause(final LNGIntVector ps, boolean learnt) {
    this(ps, learnt, false);
  }

  /**
   * Constructs a new clause
   * @param ps       the vector of literals
   * @param learnt   {@code true} if it is a learnt clause, {@code false} otherwise
   * @param isAtMost {@code true} if it is an at-most clause, {@code false} otherwise
   */
  public MSClause(final LNGIntVector ps, boolean learnt, boolean isAtMost) {
    this.data = new LNGIntVector(ps.size());
    for (int i = 0; i < ps.size(); i++)
      this.data.unsafePush(ps.get(i));
    this.learnt = learnt;
    this.szWithoutSelectors = 0;
    this.seen = false;
    this.lbd = 0;
    this.canBeDel = true;
    this.oneWatched = false;
    this.isAtMost = isAtMost;
    this.atMostWatchers = -1;
  }

  /**
   * Returns the size (number of literals) of this clause.
   * @return the size
   */
  public int size() {
    return this.data.size();
  }

  /**
   * Returns the literal at index {@code i}.
   * @param i the index
   * @return the literal at index {@code i}
   */
  public int get(int i) {
    return this.data.get(i);
  }

  /**
   * Sets the literal at index {@code i}.
   * @param i   the index
   * @param lit the literal
   */
  public void set(int i, int lit) {
    this.data.set(i, lit);
  }

  /**
   * Returns the activity of this clause.
   * @return the activity of this clause
   */
  public double activity() {
    return this.activity;
  }

  /**
   * Increments this clause's activity by a given value
   * @param inc the increment value
   */
  public void incrementActivity(double inc) {
    this.activity += inc;
  }

  /**
   * Rescales this clause's activity
   */
  public void rescaleActivity() {
    this.activity *= 1e-20;
  }

  /**
   * Returns {@code true} if this clause is learnt, {@code false} otherwise.
   * @return {@code true} if this clause is learnt
   */
  public boolean learnt() {
    return this.learnt;
  }

  /**
   * Returns the size of this clause without selector variables.
   * @return the size of this clause without selector variables
   */
  public int sizeWithoutSelectors() {
    return this.szWithoutSelectors;
  }

  /**
   * Sets the size of this clause without selector variables.
   * @param szWithoutSelectors the size of this clause without selector variables
   */
  public void setSizeWithoutSelectors(int szWithoutSelectors) {
    this.szWithoutSelectors = szWithoutSelectors;
  }

  /**
   * Returns {@code true} if this clause is marked 'seen', {@code false} otherwise.
   * @return {@code true} if this clause is marked 'seen'
   */
  public boolean seen() {
    return this.seen;
  }

  /**
   * Marks this clause with the given 'seen' flag.
   * @param seen the 'seen' flag
   */
  public void setSeen(boolean seen) {
    this.seen = seen;
  }

  /**
   * Returns the LBD of this clause.
   * @return the LBD of this clause
   */
  public long lbd() {
    return this.lbd;
  }

  /**
   * Sets the LBD of this clause.
   * @param lbd the LBD of this clause
   */
  public void setLBD(long lbd) {
    this.lbd = lbd;
  }

  /**
   * Returns {@code true} if this clause can be deleted, {@code false} otherwise.
   * @return {@code true} if this clause can be deleted
   */
  public boolean canBeDel() {
    return this.canBeDel;
  }

  /**
   * Sets whether this clause can be deleted or not.
   * @param canBeDel {@code true} if it can be deleted, {@code false} otherwise
   */
  public void setCanBeDel(boolean canBeDel) {
    this.canBeDel = canBeDel;
  }

  /**
   * Returns {@code true} if this clause is a one literal watched clause, {@code false} otherwise
   * @return {@code true} if this clause is a one literal watched clause
   */
  public boolean oneWatched() {
    return this.oneWatched;
  }

  /**
   * Sets whether this clause is a one literal watched clause or not.
   * @param oneWatched {@code true} if it is a one literal watched clause, {@code false} otherwise
   */
  public void setOneWatched(boolean oneWatched) {
    this.oneWatched = oneWatched;
  }

  /**
   * Returns {@code true} if this is an at-most clause, {@code false} otherwise.
   * @return {@code true} if this is an at-most clause
   */
  public boolean isAtMost() {
    return this.isAtMost;
  }

  /**
   * Returns the number of watchers if this is an at-most clause.
   * @return the number of watchers
   */
  public int atMostWatchers() {
    assert this.isAtMost;
    return this.atMostWatchers;
  }

  /**
   * Sets the number of watchers for this at-most clause.
   * @param atMostWatchers the number of watchers
   */
  public void setAtMostWatchers(int atMostWatchers) {
    assert this.isAtMost;
    this.atMostWatchers = atMostWatchers;
  }

  /**
   * Pops (removes) the last literal of this clause.
   */
  public void pop() {
    this.data.pop();
  }

  @Override
  public int hashCode() {
    return this.data.hashCode();
  }

  @Override
  public boolean equals(Object o) {
    return this == o;
  }

  @Override
  public String toString() {
    final StringBuilder sb = new StringBuilder("MSClause{");
    sb.append("activity=").append(this.activity).append(", ");
    sb.append("learnt=").append(this.learnt).append(", ");
    sb.append("szWithoutSelectors=").append(this.szWithoutSelectors).append(", ");
    sb.append("seen=").append(this.seen).append(", ");
    sb.append("lbd=").append(this.lbd).append(", ");
    sb.append("canBeDel=").append(this.canBeDel).append(", ");
    sb.append("oneWatched=").append(this.oneWatched).append(", ");
    sb.append("isAtMost=").append(this.isAtMost).append(", ");
    sb.append("atMostWatchers=").append(this.atMostWatchers).append(", ");
    sb.append("lits=[");
    for (int i = 0; i < this.data.size(); i++) {
      int lit = this.data.get(i);
      sb.append((lit & 1) == 1 ? "-" : "").append(lit >> 1);
      if (i != this.data.size() - 1)
        sb.append(", ");
    }
    sb.append("]}");
    return sb.toString();
  }

}
